High seas fishing would go broke without 'massive' subsidies: study

The high seas refers to areas beyond nations' territorial waters, where species like tuna tend to be overfished and migratory sharks -- 44 percent of which are considered threatened species -- often get caught in nets and killed as bycatch.

New satellite technologies that track fishing vessels are helping paint a clearer picture of how much fishing is going on in these distant seas, comprising 64 percent of the ocean and fished by a small number of nations, said the report in the journal Science Advances.

Researchers calculated that during 2014, the most recent year with complete data, the total costs of fishing in the high seas were between $6.2 billion and $8 billion.

Then they substracted the value of the catch, estimated at 4.4 million metric tons with an aggregate revenue of $7.6 billion.

This means that without subsidies, high seas would be $364 million in the red, or in the black with profits up to $1.4 billion, said the report.

"Governments subsidized high seas fishing with $4.2 billion in 2014, far exceeding the net economic benefit of fishing in the high seas," said the report.

"Governments are throwing massive amounts of taxpayer money into a destructive industry," said lead author Enric Sala, National Geographic Explorer-in-Residence.

"Without subsidies and the forced labor some of them are known for, fishing would be unprofitable in over half of the high seas fishing grounds."

Five countries accounted for most of the global high-seas fishing revenue: China (21 percent), Taiwan (13 percent), Japan (11 percent), South Korea (11 percent), and Spain (8 percent).

The study used Automatic Identification Systems (AIS) and Vessel Monitoring Systems (VMS) to track 3,620 vessels in near-real time.

Researchers added global catch data from the University of British Columbia's Sea Around Us project to estimate fishing totals.

Other researchers came from the University of California, Santa Barbara; Global Fishing Watch; and the University of Western Australia.

Researchers called for substantial reforms to high seas fishing.

"In many parts of the high seas, subsidies are propping up fishing activity to levels far beyond what would otherwise be economically rational," said co-author Christopher Costello, professor of environmental and resource economics at UC Santa Barbara.

"This implies that through targeted subsidy reforms, we could save taxpayers money, rebuild fish stocks, and eventually lead to higher value, lower volume fisheries."